The safe storage of inflammable liquids, such as petroleum products, in tanks has proved to be a more serious problem than was originally imagined. When tanks develop leaks, for one reason or another, the liquid seeps out to form pools in the surrounding low areas, and these pools may become ignited and cause widespread damage. Large ground level storage tanks at supply depots are now required to be placed separately inside levees that will prevent any leakage from spreading beyond the levees. Smaller storage tanks of 10,000-20,000 gallons found at local retail outlets may be found above or below ground level, and frequently are not protected by any type of containment system that would prevent the leaking liquid from spreading far beyond the storage tank. New installations are now being controlled by state regulations requiring some type of secondary containment system, by which is meant a system wherein the primary storage tank must also be placed in some type of secondary container to prevent the spread of leaking liquid.
In the case of existing above-ground storage tanks there is no system for providing the protection mandated by the regulations relating to new installations. Such a system is needed and the present invention provides it.
It is an object of this invention to provide a secondary containment system for horizontal cylindrical storage tanks. It is another object of this invention to provide a secondary containment system wherein the primary liquid storage tank is placed inside a larger empty secondary tank which is modified to provide all the necessary safety features and also to serve as a liquid dispensing station. Still other objects will become apparent from the more detailed description which follows.